US 3273491 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Sept. 20, 1966 E. CALVERT 3273,49!
AIR-OPERATED PRES SES Filed March 1.7, 1965 5 Sheets-Sheet 1 Sept. 20, 1966 E. CALVERT 3,
AIR-OPERATED PRESSES Filed March 3.7, 1965 5 Sheets-Sheet 2 Sept. 20, 1966 E. CALVERT 3,273,491
AIR-OPERATED PRESSES Filed March 17, 1965 5 Sheets-Sheet :5
United States Patent 3,273,491 AIR-OPERATED PRESSES Eric Calvert, Burnley, England, assi'gnor to Joseph Lucas (Industries) Limited, Birmingham, England Filed Mar. 17, 1965, Ser. No. 440,503 3 Claims. (Cl. 100-53) This invention relates to air-operated presses and has for its object to provide such a press in a convenient i orm which is safe in use but does not require a press guard.
A press according to the invention comprises manually operable means tor moving a tool to a predetermined position which is close enough to the work to ensure that if a finger is positioned in the path of movement of the tool, the tool will contact the finger before the predetermined position is reached, and means for causing airoperation of the tool when said predetermined position is reached.
It will be understood that a press as specified above will not require a press guard and will permit an operator to position the work accurately with respect to the tool. It the operators finger should be inadvertently placed in the path of movement of the tool the operator will become aware of this before the tool attains the predetermined position, but the only pressure exerted on the finger by the tool is controlled by the operator, who will need to move the finger before the press is air-operated. Preterably, the predetermined position is only attained with the tool actually in contact with the work, but a small clearance would be permissible without impairing safety.
One example of the invention will now be described with reference to the accompanying drawings in which:
FIGURE 1 is a side elevation view of the machine,
FIGURE 2 is a front elevation view, partially in crosssecti-on on the line IIII in FIGURE 1,
FIGURE 2 is a cross-sectional plan view on the line I IIIII in FIGURE 2,
FIGURE 4 is a view on the line IV- IV in FIGURE 1, and
FIGURE 5 is a diagrammatic lay out of the pneumatic circuit of the machine.
In this example there is provided a body incorporating a pedestal on which work is supported, and a hollow housing 11 above the pedestal. Within the housing 11 is slidably mounted a tool holder 12 which supports a tool (not shown) which is to act upon the work. Moreover, above the housing is a cylinder 13 which contains a hammer M which is spring-loaded to an upper position. The arrangement is such that when air is admitted to the upper end of the cylinder 153 through the pipe 15, the hammer 14, is forced downwardly into contact with the tool holder 12 to impart its blow to the work. Air flow to the cylinder 13 is controlled by a two-way valve 16 which connects the cylinder either to exhaust or to air under pressure from a supply pipe 17 (see FIGURE 5) through an on-off valve 18 and pressure gauge 19. The position of the two-way valve 16 is controlled by air pressure such that the valve normally connects the cylinder 13 to exhaust, but is movable by air flowing through an auxiliary supply line 20 (see FIGURE 5) to a position in which the hammer 14 is operated.
However, the auxiliary supply line incorporates first and second valves 21 and 22 respectively, both of which must be opened before the hammer 14 is operated.
Extending from the (tool holder 12 through an elongated vertically extending slot 9 in the housing 11 is a pin 23 the ends of which engage within arcuate slots 24 in a pair of main operating levers 25, to one of which an operating arm 26 is fixed. The main levers at their ends remote from the slots 24, carry a counter balance weight 27. The levers 2-5 are pivotally connected to the body intermediate the ends thereof.
The tool holder 12 carries a pair of spigots 29 also extending through the slot 9 in the housing 11 and each passing through an arcuate slot 30 in one end of a respective one of a pair of auxiliary operating levers 3 1.
The auxiliary levers 31 are also pivot-ally mounted about the horizontal axis 28 through the extension 32 thereof. Pivotally mounted on the extension 32 of one of the auxiliary levers 3 1 (namely that seen in FIGURE 1) is a valve controlling member 33, having a pair of arms, 33a, 33b, the arm 33a being arranged to contact the upper surfiace of the main lever 25 on the side of the axis 28 remote from the slot 30, and the other arm 33b being arranged to con-tacit a push rod 36 extending through the body and coaxially with the axis 28 to engage an operating plunger 37 on the valve 21, as illustrated in FIGURE 4, whereby movement of the push rod 36 towards the valve 21 causes the plunger 37 to open this valve. Also as seen in FIGURE 4, the member 33 is rockable about an axis.
The main lever 25 on the opposite side from the valve controlling member 36 carries a cam 38 which, when the main levers are near the extreme ends of their travel, can operate a plunger 39 of the valve 22. Moreover, acting between the pin 23 carrying the main levers 25 and a bush 34 forming a part of the tool holder 12 and carrying the spigot 29 tor the auxiliary levers 31, is a coiled compression spring 35.
In use, work is positioned manually on the pedestal and the main operating levers are pulled downwardly by the operating arm 26 to move the tool towards the work. Movement of the main levers 25 is accompanied by movement of the auxiliary levers '31 by virtue of the spring 3 5, the arcuate slots 24 and 30 maintaining the distance between the pin 23 and the spigots 29 constant.
Assuming that the tool contacts the work without impediment, continued movement of the main levers 25 compresses the spring 35 and permits angular movement of the main levers relative to the valve-controlling member 36, thus rocking this about the axis 40 to move the push rod 3.6 to cause the first valve 21 to be opened. The hammer 14 is now operated, the second valve 22 having been opened by the cam 38. The position at which the second valve 22 is opened is accurately adjusted by rotation of the cam 38 so that there is no danger of the hammer being operated until it is so close to the work that a finger could not be inserted.
If an operators finger should be placed in the path of movement of the tool, the first and second valves will not be opened, and the only pressure exerted on the finger is that due to the compression spring.
Afiter the hammer 14 has operated, the main levers are released and the parts return to their rest positions.
Having thus described my invention what I claim as new and desire to secure by Letters Patent is:
1. A press comprising a hollow housing, a tool holder slidably disposed within the housing, a pair of levers pivotally mounted on the housing, one of said levers being connected to the tool holder and the other being engageaJble therewith through a spring, a fluid pressure operated device associated with the tool holder, a first valve on the housing operable to permit flow of fluid to said device to render it operative when relative movement between the two levers against the action of the spring has taken place, and a second valve operable to permit flow to said device, said second valve being so positioned on the housing that it can only be operated when said tool holder has reached a predetermined position which will preclude the insertion of an operators finger beneath the tool holder, said device only being operable when both said first and second valves have been operated.
2. A press comprising a hollow housing, a tool holder slidably disposed within the housing, a pair of levers pivotally mounted about a common axis on the housing, one of said levers being connected, at a position removed from the axis, to the tool holder and the other lever being engageable there-with through a spring, a fluid pressure operated device associated with the tool holder for imparting a blow thereto when the tool holder has reached a predetermined position, a first valve on the housing operable to permit flow of fluid to said device to render it operative in response to relative movement between the two levers, against the action of the spring, and a second valve operable to permit flow to said device, said second valve being operated by said levers when said tool holder has reached said predetermined position which will preclude the insertion of an operators finger beneath the tool holder, said device being operable only when both said first and said second valves have been operated.
References Cited by the Examiner UNITED STATES PATENTS 721,101 6/1903 Morris 83--554 1,051,665 1/1913 Bates 83554 X 1,579,138 8/ 1 926 Zimmer 83554 2,941,428 6/ 19 Riggio et a1. 3,095,803 7/1963 Lindero-t'h 53 X WALTER A. SCHEEL, Primary Examiner. BILLY I. WILHITE, Examiner.